1. Field of the Invention
This invention relates to a composition for use in the removal and/or prevention of build-up of slag on heat transfer surfaces. In particular, the invention relates to a composition for use in the glass manufacturing industry for the removal of slag from the heat recovery area of the furnace caused by deposits from gases exhausting from the furnace proper.
2. Description of the Prior Art
A glass manufacturing furnace operates at a temperature in the range 1400.degree.-1700.degree. C. Accordingly, gases exiting from the furnace do so at very high temperatures. Heat from the gases is recovered in a heat recovery chamber or recuperator which contains a plurality of heat exchange elements, normally pipes, containing a heat absorbing fluid. Build-up of slag on recuperator pipes is a serious problem in glass manufacture and allied industries.
At present in the glass industry slag (deposits) is allowed to build-up on the heat transfer surfaces with a progressive loss of heat transfer and recovery and hence loss of energy. Eventually the build-up of slag reaches a particular level when heat transfer is no longer adequate, the furnace is shut down and the slag is removed from the heat transfer elements by scraping. The normal shut down period in a large plant is one month per year. Shut down of the furnace is an extremely expensive operation which is avoided by the glass industry unless it is essential. By allowing slag to build-up losses in heat transfer energy occur which have been estimated to be approximately 7-14%. It will be appreciated that this is very costly to the glass industry.
Accordingly, it will be appreciated that any method of removing slag from recuperator tubes during normal operation would be a significant breakthrough.
The components of the slag deposited from gases exiting from a glass making furnace are sodium sulphate, phosphor and lead.
It is an object of the present invention to provide a composition which will remove slag which has built-up on the aforementioned heat transfer surfaces and which can also be used to prevent future build-up of slag on said surfaces.